Selective spin-wave nonreciprocity in an engineered chiral magnonic crystal without Dzyaloshinskii-Moriya interaction

Chirality is pivotal in magnonics, particularly for achieving spin-wave nonreciprocity which is critical in advancing spin-wave-based communication and logic operations. In general, chirality in magnetic systems is realized through the interfacial antisymmetric exchange interaction, namely, the Dzyaloshinskii-Moriya interaction, which is an intrinsic phenomenon occurring at the buried interface of a ferromagnet and heavy metal. In this work, using micromagnetic simulations, we present a different route to achieve spin-wave nonreciprocity using an engineered chiral magnonic crystal, where we artificially created in-plane twisted spin textures by imposing certain handedness in the structural geometry. The manipulation of the relative arrangement of these chiral enantiomers led to spin-wave nonreciprocity, which could be tuned by selecting different channels within the crystal, with additional versatility in the resonant mode frequency. Further adjustment of the external magnetic field strength confirms that the spin-wave directionality originates from the spin texture. This enables additional control over the band gap and mode propagation characteristics by external field tuning. Our work provides an innovative route to simultaneously access opposite spin-wave directions in consecutive channels, which makes this system competent for a real on-chip magnonic diode, with predefined paths for counterpropagating information.